Electronic television transmitter



Patented Feb. 9, 1943 Walter Heimann, Berlin, Germany; vested in the Alien Property Custodian Application July E24, 1940, Serial No. 347,126 In Germany July 25, 1939 6 Claims.

This invention relates to means for producing with the aid of a plane cathode an electron image that corresponds to an optical image, and it consists in certain features of novelty which will appear from the following description, reference being had to the accompanying drawing, in which Fig. 1 is a diagrammatic sectional view showing certain features of a prior arrangement of this kind, Fig. 2 is a view similar to Fig. 1 and which represents an embodiment of the invention, and Fig. 3 is a sectional View illustrating a second embodiment thereof.

In Figs. 1, 2, 3K denotes a plane photocathode which forms part of the wall of a closed chamber D, while A indicates an accelerating anode joined to chamber D. The dotted lines represent potential lines or surfaces.

As will be seen in Fig. 1, those potential lines which are in close proximity to the cathode are parallel to it or are convex with respect to the anode A, whereas certain potential lines farther removed from the cathode are concave with respect to the anode A. The latter potential lines act to collect and direct the electrons emanating from the cathode and provide for the electronoptical representation of them. This arrangement enables a comparatively undistorted reproduction from a large plane cathode.

The invention aims to employ still larger plane i cathodes and thereby to improve the quality of reproduction. To such end not only the potential lines in close adjacency to the cathode, which are not much different in potential from the cathode, are caused to run parallel with the plane portion of the cathode, but also those potential lines or surfaces Whose potential is relatively high compared with the emission velocity of the electrons at the cathode, for example about ve times the velocity. Only those potential lines the potential of which is in excess of about five times the electron emission velocity should be concave with respect to the anode in order to produce the desired collecting and directing effect.

Fig. 2, that illustrates an arrangement according to the invention, shows a diaphragm BI disposed in a closed cathode chamber D and given a potential which is about one tenth of the anode voltage. this diaphragm shaped as desired.

Fig. 3 shows an additional diaphragm B2 which in the case disclosed by Fig. 3 has the same potential as the cathode. In other cases, how- The potential field is by ever, any desired potential, either more positive or preferably more negative than the cathode, may oe imparted to diaphragm B2.

What is claimed is:

1. An electron image device comprising a large surface plane cathode adapted to emit electrons, an anode for receiving said electrons, a chamber having a diameter greater than said cathode mounted between said cathode and said anode and joined to said cathode, means for producing an electrostatic field in said chamber having equi-potential lines, and a diaphragm in said chamber for shaping "equi-potential lines of said ileld within said chamber, said diaphragm being mounted coaxial with said cathode and having an opening therein in the order of the diameter of said cathode and said equi-potential lines being substantially parallel to said plane cathode in the region adjacent said diaphragm and between said diaphragm and said cathode.

2. An electron image device according to claim 1 wherein said equi-potential lines in the region adjacent said diaphragm have a potential at least five times as great as the potential corresponding to the emission velocity of the electrons from said cathode.

3. An electron image device comprising a large surface plane cathode adapted to emit electrons, an anode for receiving said electrons, a chamber having a diameter greater than said cathode mounted between said cathode and said anode and joined to said cathode, means for producing an electrostatic eld in said chamber, having equi-potential lines and a diaphragm provided with a central opening in the order of the diameter of said cathode in said chamber for shaping equi-potential lines of said field within said chamber, said diaphragm being mounted coaxial with said cathode and having a potential different from that of said chamber.

4. An electron image device according to claim 3 wherein said anode has a positive potential with respect to said cathode and the potential of said diaphragm is one-tenth of the potential of said anode.

5. An electron image device according to claim 3 wherein said plane cathode is a photo-cathode.

6. An electron image device according to claim 3 further comprising a second diaphragm of substantially the same form as said diaphragm iirst named mounted between said first-mentioned diaphragm and said anode and in said chamber.

WALTER HEIIVIANN. 

